The emails former Secretary of State Hillary Rodham Clinton turned back over to the government last year contained “gaps,” according to internal department messages evaluating her production.

Mrs. Clinton took office on Jan. 21, 2009, but the first message she turned back over to the department was dated March 18, and the earliest-dated message she herself sent was on April 13, or nearly three months into her time in office, according to a message obtained through an open records request by Judicial Watch, which released it Monday.

Mrs. Clinton has said she continued using a previous account she’d used during her time as a senator for business at the beginning of her time as secretary, but the differing dates between the first email received and the first sent raise still more questions.

SEE ALSO: Senators seek ways to get Pagliano to talk about Clinton emails

The revelation of the gap comes even as the legal situation grows more complicated.

Two Senate committee chairmen pushed Monday to try to find out just how deeply the Justice Department’s investigation into the Clinton email server has gone, as the two senators tried to figure out ways of getting Bryan Pagliano, the tech staffer who helped set up her email server at her home in New York, to spill what he knows.

In a letter to Attorney General Loretta E. Lynch, Sens. Chuck Grassley and Ron Johnson asked the government to say whether it would object to a “proffer” session between the senators and Mr. Pagliano, where he could detail, off the record, what he knows without having to worry about it being used against him in a prosecution.

Meanwhile, the State Department met with more resistance from the myriad groups who have sued to pry loose emails from Mrs. Clinton and her top aides, and who told a federal court Monday they don’t want to see the proceedings centralized in a single judge.

“State should have anticipated many years ago that it would experience an increase in [Freedom of Information Act] requests for records about Mrs. Clinton’s tenure as secretary of state, and planned accordingly. Yet apparently nothing was done at any time in the last six years to prepare for this highly foreseeable expense, and state now relies on its own failure to prepare as justification to delay complying with its obligations under FOIA,” Jason Leopold, a journalist whose case has prompted the ongoing release of Mrs. Clinton’s emails, said in a court filing made by his lawyer.

Mrs. Clinton declined to use the State Department’s regular email system during her time in office, instead setting up a server at her home and using an account on that server. Many of her top aides also used personal accounts or accounts on the server Mrs. Clinton kept.

Mrs. Clinton says she didn’t break any laws, though the State Department and at least one federal judge have said she violated policy. And the use of non-State.gov accounts has shielded much of the information from subpoenas, congressional inquiries and open records requests — until now.

The State Department would like to shield them a little longer, having asked the federal district court to consolidate more than 30 search lawsuits that have been filed.

Several judges have already indicated they’ll object to that, however, and have turned down delay requests in the meantime. The judges are also pushing the State Department to be more forthcoming in how many emails it is sitting on from Mrs. Clinton’s aides.

The revelation of a possible email gap in Mrs. Clinton’s own records came out of the State Department’s response to one of the open records cases.

According to Eric F. Stein, a State Department official who wrote the evaluation of Mrs. Clinton’s messages, there were “gaps” of several weeks at the beginning and end of her records.

For example, the last message she turned over was dated on her last day in office, Feb. 1, 2013, and it came from Cheryl Mills, one of her top aides. But the last message Mrs. Clinton herself sent and turned over was dated Dec. 30, 2012, a month before she left office.